Hammers and hammer-like tools have been known in the art for many centuries, and are used to drive a nail or other fastener into a working surface, e.g., wood, concrete. Hammers comprise a user-holdable handle to which a head is attached. While the handle may be fabricated from a non-metal material such as wood or fiberglass, the hammer head is made from a durable metal. A durable metal, e.g., steel is preferred since the hammer head is used to forcibly strike a typically metal nail or other joining device.
It is a relatively easy task to start a nail into the surface of the material being worked up when the material is not substantially higher than the head of the hobbyist, carpenter, contractor, or other person using the hammer, collectively the "user". The user simply holds the nail (or other joining device in one hand), and strikes the head of the nail with the head of the hammer, while holding the hammer in the other hand. Once the nail has been struck and is at least partially lodged into the material being worked upon, the user needs only one hand to deliver further hammer blows to drive the nail home.
However starting a nail into a work surface can be rather difficult if the work surface is substantially higher than the user's head. The position to be nailed may be within range of the hammer head but may be slightly beyond reach of the user's free hand. The task of starting a nail into the work surface can be exceedingly difficult when the surface is completely overhead, for example a ceiling to which sheet rock or the like is to be attached. Carpenters using a hammer during a framing operation often need to hold the work surface with one hand, while attempting to use a hammer to start and drive a nail with the other hand.
Such task would be simplified if the nail or other joining device could temporarily be attached to the hammer head, with the sharp end of the nail facing away from the head.
It is known in the art to apply a tacky adhesive to the striking surface of a hammer head, which adhesive can retain the nail at least for the initial hammer blow. Understandably it is necessary not merely to retain the nail to the hammer striking surface, but to retain the nail at a proper starting angle. Adhesives can be messy in practice, and grease, oil, dust and the like on the nails being used can rapidly reduce the effectiveness of the adhesive. A nail that has detached itself from a hammer head may cause injury to nearby persons.
More preferably, magnetic hammer heads are known in the art. For example, USP 4,073,327 to Pearson (1978) disclosed a modified hammer head in which a central portion of the original head is removed and replaced by a magnetic material. USP 3,580,312 to Hallock (1971) disclosed another configuration in which the ferrous head of a conventional hammer includes at least chamber formed at right angles to the striking surface. A permanent magnet is sealed within each chamber to magnetize the hammer head.
Note that magnetic hammers such as disclosed by Pearson and Hallock are essentially dedicated hammers in that the magnetic feature is always present, at least until the magnetism is lost. Stated differently, it is not feasible to instantly render a Pearson or Hallock hammer non-magnetic, then render it magnetic, then non-magnetic, and so forth, depending upon the nature of the task at hand.
Although prior art magnetic hammer heads are useful for starting nails in difficult to reach locations, especially ceilings, dedicated hammer heads such as disclosed by Pearson and Hallock have certain disadvantages. The repeated impact of the magnetized hammer head against nails can result in a loss of magnetism in the hammer head. Since the above-described prior art hammers use a dedicated hammer head, e.g., a head that has been permanently modified or manufactured to be magnetic, it will eventually be necessary to replace the entire hammer head. But magnetic hammer heads are expensive to replace. Further, replacing a hammer head involves forcibly removing the head from the hammer end of the handle, typically by digging out a metal wedge that is driven into the handle end. Replacing the hammer head more than once or twice can require replacing the handle as well, as the region into which the wedge is driven will soon weaken.
But even if replacing a dedicated magnetic hammer head were inexpensive and easy, and such is not the case, the user may not always want the hammer head to be magnetic. For example in many applications there will be no need for a magnetic hammer head. Yet if the user were to inadvertently drop the hammer head into a box of nails, the result would be that many nails would be magnetically attached to the hammer head. The user would then have to waste time removing all but perhaps one of the nails. Further a magnetic hammer head could be a disadvantage when working in an area that might be sensitive to magnetism. For example if the magnetic hammer were used in a computer room where storage diskettes were near the work surface, there is a possibility that data stored on the diskettes might become corrupted. Obviously such potential risk would not exist if the hammer head were not magnetic.
Thus, there is a need for a mechanism that can render the head of a hammer magnetic when desired, but non-magnetic otherwise. Preferably such mechanism should be retrofittably useable with existing hammer heads without requiring modification to the original hammer head. Finally, there is a need for such mechanism that can be inexpensively and readily fabricated, and that can be used even by laypersons.
The present invention provides such a mechanism.